Listening Comprehension is widely acknowledged as one of the more important skills in our society, yet there has been a paucity of research in developing construct valid instruments to measure it. The objective of the proposed study is to develop a state-of- the-art construct measurement system for listening comprehension. The capacity to develop such a measurement system is made possible through item engineering methodology. The central theme of the methodology is simple, yet elegant: until we understand what characteristics or features of test items or instructional tasks are responsible for making such tasks difficult or easy, we do not really know what we are measuring or teaching. Once the features responsible for task difficulty have been specified, it becomes possible to truly "engineer" test items and instructional materials for a given domain. The following activities will be performed. 1. Build and test a theory of Listening Comprehension task difficulty. 2. Develop 200 listening tasks that span the developmental continuum from 3 years through advanced adult level. 3. Design a Listening Comprehension Scale for expressing task difficulty and level of achievement. 4. Design a plan for creating a rich criterion and normative frame of reference for score interpretation. 5. Design Phase II.